Maslach and Jackson first introduced the concept of ‘burnout’- a state of physical and emotional exhaus- tion emerging from work conditions- in 1980. The importance of investigations of burn out lies in the fact that it is directly related to the quality of teaching. There are three basic criteria set to predict, evaluate, and prevent burnout: depersonalization, emotional exhaustion, and personal accomplishments. Teachers in Iran are not an exception to developing burnout, and neither are Iranian EFL teachers. To investigate the current situation of teacher burnout in general and the three criteria set by Maslach and Jackson among Iranian EFL teachers, the researchers selected 40 junior high school, 40 senior high school, 40 university, and 40 private English institute EFL teachers, and sought their burnout levels via Maslach Burnout Inventory. The statistical analysis of the data revealed the existence of significant dif- ferences among the burnout levels of these four groups of EFL teachers. Junior high school teachers re- ported the highest degree of reduced personal accomplishment whereas the highest levels of depersonali- zation, emotional exhaustion, and total burnout were reported by senior high school teachers. University teachers reported the smallest degree of burn out.